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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22012
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Lennox furnace G32V: alternating light flashing fault code.

Customer Question

Lennox furnace G32V: alternating light flashing fault code. Furnace doesn't want to start. We have replaced the flame sensor 40L81, and still getting fault code. Can you help?
Submitted: 4 years ago.
Category: HVAC
Expert:  BillyHvac replied 4 years ago.



does the burner ever actually fire when this code appears?



Customer: replied 4 years ago.
Yes, sometimes.
Expert:  BillyHvac replied 4 years ago.


Thank you.


So we dont have all the time: exhaust starts, flame lights, flame goes out.

And we also dont have exhaust starts, flame never lights all the time?


We a combination of lighting and not lighting all with the slow altrenating flash?



Customer: replied 4 years ago.

It starts, runs for a little bit, then goes out.


Yes, combination of lighting and lighting.

Expert:  BillyHvac replied 4 years ago.

First check all the ground wires. Furnace to board and furnace to incoming ground.


If the ground wires are all tight and intact, then it would point to poor ignition circuitry in the board.



Customer: replied 4 years ago.

I have checked ground circuits. How do I check circuitry in the board?


Expert:  BillyHvac replied 4 years ago.

The field testing is somewhat limited as circuit boards are not field repairable.


however here is a service manual to assist you in troubleshooting.


I believe you will find itto be circuit board if indeed the code is always the same...unit lights and does not light, and grounds and sensor check ok.


Link -



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